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Temperature-mediated switching of magnetoresistance in Co-contacted multiwall carbon nanotubes

2003; American Institute of Physics; Volume: 83; Issue: 5 Linguagem: Inglês

10.1063/1.1597965

1520-8842

Saikat Chakraborty, Kevin Walsh, Bruce Alphenaar, Lei Liu, Kazuhito Tsukagoshi,

Quantum and electron transport phenomena

We present temperature-dependent measurements of the magnetoresistance in ferromagnetically contacted multiwall nanotubes. At low temperature, the resistance increases sharply near zero-field due to misalignment of the contact magnetizations. As temperature increases, the resistance peak transforms into a resistance dip, with a peak-to-valley ratio of similar magnitude, but opposite sign. The resistance switch has a distinct temperature dependence compared with the background magnetoresistance, suggesting that the two have different origins. We propose that a ferromagnetic transition near the contact interfaces reverses the polarity of the injected spin, and changes the sign of the resistance switch.